beyond the mssm from the little hierarchy problem to the baryon asymmetry of the universe

Beyond the MSSM

From the little hierarchy problem to the Baryon Asymmetry of the Universe

Kfir Blum

Advisors:

Yossi Nir and Eli Waxman

Supersymmetry (SUSY) is a great idea

It fixes the fine tuning problem

MSSM = simplest SUSY extension of SM Higgs sector extremely predictive:

more so than in SM!

…But it does not completely solve the tuning – little hierarchy problem remains

The little hierarchy problem

MSSM: at classical level, mH< mZ=91 GeV ! LEPII: mH>114 GeV

need large quantum corrections; can do with very heavy stops, mst>TeV

This implies % tuning

If additional DOF heavy M >> mZ, general way to proceed is via effective field theory:

Beyond MSSM

MSSM ain’t the whole story(we know this: for one, it isn’t enough to break SUSY)

Can additional DOF solve little hierarchy problem?

BMSSM

• Expand in powers of m/M, m ~ mZ << M

• Higgs sector:

)Approx’( SUSY + leading m/M Only two operators !

• In the scalar potential:

For M < 10 TeV,

More than enough to lift mH above LEP at classical level

See e.g. Dine, Seiberg & Thomas,

Phys.Rev.D76:095004,2007

BMSSM: Implications for vacuum stability and Cosmology

• Vacuum stability

• Dark Matter

• The electroweak phase transition and electroweak baryogenesis

Blum, Delaunay & Hochberg,

Phys.Rev.D80:075004,2009

Bernal, Blum, Losada & Nir ,

JHEP 0908:053,2009

Blum, Delaunay, Losada, Nir, Tulin,Work in progress

Bernal, Blum, Losada & Nir ,

JHEP 0908:053,2009 Blum & Nir ,

Phys.Rev.D78:035005,2009

MSSM

BMSSM

BMSSM Higgs potential non trivial.

Raise mH tunneling problem ?

Vacuum stability

…SUSY implies:

Constraints remain:

• Must not overcome gauge couplings• Upper bound on M

MSSM

BMSSM

Baryon Asymmetry of the Universe cannot be solved within SM

MSSM EWBG – little hierarchy amplified

need mH~114 GeV, but also light stop

other stop very heavy big little hierarchy

BMSSM:• Can have 2 light stops! No hierarchy• New couplings CP violation• Spontaneous EWBG

BMSSM

Electroweak Baryogenesis

Summary

* MSSM little hierarchy problem – due to constrained Higgs sector, solved Beyond-MSSM * Vacuum stability – SUSY renders effective theory simple & consistent

* Implications for Cosmology

– Natural EW Baryogenesis with 2 light stops – DM scenarios )bulk region reopens(

Outlook

* Spontaneous EW Baryogenesis

* Light stop phenomenology

* Microscopic realizations

Thanks!

Xtras

If…

•BMSSM respects R-parity

•Approximately SUSY (msoft<<M)

SUSY breaking via spurions

Pure Higgs:

Only 2 new operators!…enough to solve little hierarchy problem

Choice of basis

Leading mass shift

Dimension 6 scalar term,

and condition for neglecting it

2-loop thermal corrections associated with dim 6 term

Effective potential

EWPT I

EWPT – Barrier Formation

• First order: barrier forms between EW breaking and conserving minima

• Barrier height depends on light scalar dof coupling to the higgs field, and on thermal screening

• In SM, only gauge bosons contribute to barrier

• In MSSM, negative soft squared-mass can reduce thermal screening for stops, making them the dominant player by far

BMSSM higgsinos

Chargino-chargino-scalar-scalar

terms and modifications to the mass

matrices exist as well

Most natural parameter spacefor MSSM DM:Bino annihilates via lightsfermion exchange.

Example – mSUGRA Bulk Region.

If sfermion spectrum correlated )light sleptons light stops(,LEPII kills bulk region, since stopsmust be heavy.

BMSSM Dark Matter

BMSSM:

• mH decoupled from mst

efficient sfermion t-channel,

bulk region lives• Stop co-annihilation region

Also:

• Higgs resonance channel,

• Modified Higgsino couplings